Project 1 will explore the possibility that the calcium-dependent regulatory mechanism controlling "latch" involves the actin-binding protein, caldesmon. Continuing studies are those of the actions of divalent cations on regulatory mechanisms using skinned fibers, agonist-stimulated mobilization of myoplasmic calcium, the role of intracellular and extracellular calcium pools and the plasma membrane in regulating cell calcium, and various structural studies of the myosin molecule present in smooth muscle. Project 2 will continue studies of medial hypertrophy and the role of cellular hypertrophy and hyperploidy in chronic hypertension. The properties of tetraploid cells in vivo and in vitro and the mechanisms involved in injury-induced smooth muscle cell proliferation will be pursued. Tissue culture study will focus on the effects of growth factors and vasoactive agonists on cytodifferentiation. Project 3 will continue the structure function investigations of microvessels and the role of endothelial cell dependent relaxing factor in modulating contraction in resistance vessels. Project 6 will focus on better chromatographic techniques to separate and identify various inositol phosphates and phospholipids and to determine the effects of diglycerides on cell membrane electrophysiological characteristics and to use single channel recording to determine ionic selectivities. Project 7 will develop a polyclonal antibody to the renal juxtaglomerular cell membrane allowing improved isolation of the cells and to continue studies of the molecular processing of renin. The reverse hemolytic plaque assay will be employed to quantitate the role of calcium, atrial naturetic factor, and other agents which may control renin secretion from the jg cells. Project 8 will use fluorescent indicators to measure cell calcium and its relationship with occupancy of angiotensin receptors and receptors aggregation and capping. This will be correlated with studies of plasma membrane and isolated receptors. Finally, a variety of studies will be pursued to elucidate the mechanism and identity of the endothelial cell dependent relaxing factor. Most of the projects draw heavily upon the support and services of the Cell Culture Core, Spontaneously Hypertensive Rat Colony, and the Electronmicroscopic Core.